You can find the Pentacon Six manual at:

http://www.commiecameras.com/ddr/p6/manuals/index.htm

This is Nathan Dayton’s excellent “commiecameras” website. 

Oldtimer Cameras of Hatfield, England, can also provide operating manuals, but not to view on-line.  In my experience, manuals from them are photocopies of the originals.
Their website is www.oldtimercameras.com. 
e-mail sales@otcworld.co.uk
Fax +44 1707 273773

Deutsche Bedienungsanleitungen
You can find German-language operating manuals at http://mitglied.lycos.de/kamerageschichte/  Click on the Download link.

Note about German manuals added 24th June 2007
I am sorry that this link doesn’t currently work.  (I don’t have any personal knowledge of the owner of that website.)
As an alternative source for a manual, I suggest that you contact Rolf-Dieter Baier.  See http://www.baierfoto.de/Instructions.html
He currently shows a Praktisix manual.  This is similar to, but not the same as, a Pentacon Six, but he may have a manual for you.  You can e-mail him in English or German.
If Herr Baier can’t help, I suggest that you set up a search on eBay.de with the key word Bedienungsanleitung or Gebrauchsanweisung.
Important I suggest that you follow the instructions on this website on loading the camera; following the instructions in the manual can result in problems!
See details here.